View Full Version : LED Diffuser

05/29/2016, 02:55 PM
Any recommendations on acrylic or similar (polycarbonate, styrene) sheet to use under LEDs to diffuse light? I've noticed acros grow/look better in my frag tank than the same ones in the display. The frag tank is lit by Chinese LEDs (similar/same to Mars Aqua 165 watt units, and with optics) which are suspended about 20 inches above the water. The display tank has a canopy which limits the height to about 6 to 8 inches over the water (canopy also houses a couple of T5s, otherwise I'd just ditch the canopy and suspend the lights higher - though I also like the way the canopy prevents you from seeing the light source). I should also mention the LEDs in the display tank are the Reefbreeders Photon line (now discontinued but very similar to the common "reef" Chinese LEDs over my frag tank) flanked by a couple of older Reefbreeders 120 watt LEDs without optics (ordered that way due to the canopy height limitation). I'm suspicious the main difference between the frag tank and display tank is mostly due to the height of the LEDs. I'd raised the frag tank LEDs from about 10 inches to about 20 inches about a year ago, and not long after the frag tank corals have looked much better - deeper colors, faster growth, and polyps far extended. Since I'd like to keep my canopy I'm looking for other ways to compensate for the lights being so close to the water surface, and figure a diffuser might help. I've seen information on the forums here and there about diffusers, but more to reduce the disco ball effect and banding than anything else. Maybe the two phenomena are related (i.e. disco ball effect and corals getting blasted with only certain wavelengths when too close to the source).

So anyone have a recommended material/source for a diffuser I can put under my LEDs? I've been checking other threads and one of the materials being used (as late as early this year) was a film from a vendor named BerlinWallpaper - but they are now out of business. I've looked at acrylic sheet from Evonik (their brand Acrylite in the LED line; the colorless LED SignFlex has an 88% transmittance, the best of their LED line which is made to eliminate "hotspots," which I think might be the reason LEDs close to the water surface may be a problem), as well as the Markolon polycarbonate (the appropriate one for LED diffusers seems to be their Lumen XT - really expensive and only large sheets). Home Depot even carries some frosted acrylic and styrene (the latter of which is really cheap, but only in sizes suitable for picture frames which would be ok given the sizes of my fixtures). Any recommendations are appreciated, especially if accompanied by PAR/transmission numbers. That's one issue I've noticed perusing the various manufacturers' product lines - transmission varies by A LOT - as low as a few percent to about 92% (the expensive Markolon Lumen XT). TIA